Ship&#39;s gyroscopic-compass set.



E. A. SPERRY.

. SHIP'S GYROSCOPIC COMPASS SET.

APPLICATION FILED SEPT.25. I909- Patented Oct. 2,1917.

4 SHEETS-SHEET l- INVENTOR E. A. SPERRY.

SHIPS cvnosc'omc COMPASS s51.

APPLICATION FILED SEPLZS. I909- Patented Oct. 2,1917,

4 sums-sum s.

E. A. SPERBY. SHIPS GYBOSCOPIC COMPASS SE1. APPLICATION FILED SEPT.25. i909.

Patented Oct. 2, 1917.

4 SHEETS-SHEET 4.

FT QE.

ELMER A. SPERRY, or BROOKLYN, NEW YORK, ASSIGNOR T0 SPERRY cYnoscorn 00., or BROOKLYN, NEW YORK, A conrona'rron or NEW YORK.

SHIPS GYROSGOPIG-COMPASS SET.

Specification of Letters Patent.

Patented Oct. 2, 1917.

Application filed September 25, 1909. Serial No. 519,533.

purposes of navigation, and it consists in various details of construction, methods of indicating direction in various parts of a ship upon which the apparatus may be mounted, and also apparatus for recording the indications or directions, and the invention also involves the application of certain principles which it has been found best to employ with regard to the relation between the ship and'the apparatus, and comprises means for properly positioning the apparatus on shipboard with'reference to the centers of gravity and oscillation, both laterally and longitudinally.

On steel ships, such, for instance, as menof-war, submarines, etc., it is desirable to employ, as means of indicating direction, ap-

paratus not subject to magnetic disturbances nor magnetic shielding effect of the masses and walls of the ship, including the armor plate and the ships machinery, especially when the apparatus is placed below the water line in an attempt to increase its security. In this case especially it is necessary that the device should transmit its indications to a number of different points on shipboard and also that the movements of the ship should be recorded. Furthermore, the apparatus should be guarded against shocks and vibrations in so far as'possible, and also be preserved against the ballistic efl'ect of acceleration and retardation ressures however produced, as by oscillations when they are applied at some considerable distance from the center about which the oscillation occurs. Unlike the magnetic compass the gyroscopic compass is peculiarly susceptible to those influences responding to them through the gyroscope reactions, to throw the indication away from" the true north; the organization, as a whole, to be successful should therefore provide means adapted to these peculiar needs and for overcoming them and also adjusted to shield thecompass when used upon a moving or movable support, such as a ship. The following specification describes one form or one embodiment of means whereby these objects may be attained.

Figure-1 is a vertical section of one form of gyroscopic compass, showing also the transmitter.

Fig. 2 is the supporting inertia-weight and spring-in side elevation, also the adjusting means for the spring.

Fig. 3 is a sketch in elevation of the same part at right angles to Fig." 2. v

Fig. 4: is a detail of the compass card carrier and insulated mercury cups for establishing electric circuits.

Fi s. 5 and 6 are diagrams of electric circults ofthe apparatus and system, including the indicators or repeating compasses.

Figs. 7, 7 8 and 8 show the circuit relations between the transmitters and .repeaters.

Fig. 9 shows a section of the Hf wheel of the gyroscopic compassalso inc ing. and motor.

Fig. 10 shows a detail of the construction shown in Fig. 9.

11 shows a detail of the permanent circuits or connections of one ofthe indioators.

Fig. 12 is'a diagrammatic wiew of a side elevationof the ship showing the relative position of the apparatus and the axis of some of the ships motions.

. The apparatus of the first four figures may be located within the binnacle, or other suitable support, or it may belocated in the hold ofv the boat or between decks and is preferably so located with reference to the axis of roll and pitch, so that these motions have the. minimum effect, or practically no effect, upon the pendulo'us mass of the gyroscope.

sing casv The gyroscope rotor or spinning mass,

constituting the controlling factor which operates through the well-known gyroscopic principles to establish and maintain a true meridianal direction, is spun preferably by an electric current which may be either d1 rect or alternating, the latter preferred.

' This may consist of either three two or sinof the compass are actuated by electric cur- .rents other than those above described, that is, currents having diflerent characteristics, such, for instance, as difierent electrical potentials, or by direct current as distinguished. from alternating current. And it is my plan to supply these currents from a unitary or common energy supply, or they may be developed by a common mechanical source such, for instance, as-generator 15 Fig. 5, which may consist of a D. C. generator andan A. C. generator driven from'the same power source, or these two may be a unit, more or less integral and A. C. leads, terminating in the usual slip rings, shown at right may be employed, the commutator of the left. As to the detail of this common or unitary source of energization for operating the navigation system, it should be pointed out that .I have planned my system to be self-contained and the various kinds of elec. tric current required for the operation are supplied from the same energy sourceby either supplying the motor or rotary factor,

1 or factors, of the mechanical or other source or sources of supply, or by any of the various transformers required to convert the ships electrical supply into the various forms or kinds of electric current required to operate the various factors going to make up my complete. gyro navigation equipment, and for securing results which are not only impoftant but believed to be entirely unique,

as herein set forth.

The rotor of the. gyroscope is contained in the inclosure or casing 16, preferably sealed or practically so, and supplied with heat radiating means such as ribs 16. The rotor is provided with a heavy overhanging rim (58) and a hollowed out center into which fits the stator (59). Said stator is made as shown in Fig. 10, with fingers (62) to aid in dissipating the heat from the stator windings 60. The rotor shaft is supported in ball bearings which are lubricated from oil wells (56) by means of oil rings.

57 is a tube to equalize the oil in the wells. t The specific features of the gyro-rotor shown in Figs, 9 and 10 are not claimed herein, but are reserved for my co-pending application #634594-gyroscopic apparatus, filed June 21, 1911. The casing 16 is suspended from above and constitutes a pendulous mass which is suitably and adjustably supported at a point above its center of gravity as by the float 17, preferably of sheet or wrought iron or steel, partially submerged in mercury or other liquid within the tank 18,

15. C. generator being shown at the masses 1 The Cardan ring 20 supports the structure by a suitable pivot such as lmifeedges 20 the ring in turn being supported to the normal by knife edges 21, from the ship or part thereof. I prefer, however, the in termediary of an inertia factor represented in the one form by the weight 21' upon which knife edges 21 bear, the weight being fulcrumed upon a suitable support at point 22, and supported by spring 23 by means of the upright rods 22' and adjustable stops 22" secured to said weight 21. It should be noted that the trajectory of these stops in turning about 22 indicated by a dotted line, maymake an angle with the horizontal which is so selected that it approaches coincidence with the inclination of the spring curve at'its working position. This arrangement imparts to the general scheme the important quality of being suspendedupon a spring of nearly infinite length, giving to the supporting mass an exceedingly long natural period of oscillation, which is moreover adjustable, and by this means may be so arranged that it is not likely to phase with any of the ordinary vibrations or motions reaching the apparatus. The instrument is guarded against augmentation of movement or vibration by this arrangement. The inertia factor of the 1 weight also guards the instrument by virfarther from the fulcrum than are the knife edges 21 gives it an added advantage of functioning Without unduly increasing thev masses.

Bent lever 23' pivoted at 23" to a stationary support carries at the end of one of its arms a hanger or stirrup 23 for supporting the spring A bolt 23 secured to a stationary support is threaded to engage the other arm of the lever, suitable"adjusting nuts 23 being provided to vary the angular position of the bent lever and thereby to adust the position and resistance of spring 23.

The pendulous mass, supported from above tween the relatively stationary parts 18 and 20 and the more sensitive central orienting portion which moves with the gyro. It may be noticed that switches, or circuit manipulating devices, for the proper control of and 21 which move in azimuth with saidtrough and compass card (Figs. 5 and 6).

Where a float is employed a tank cover is provided as shown at 18. Carried by a suitable part, such, for instance, as the tank 18 itself, is the damper plate 27, consisting of a spherical plate of sheet copper, aluminum or the like, located in more or less close proximity to a damping magnet 28 attached for example to the lower part of casing 16. The current to this magnet is controlled and adjusted-by a switch 28'. (Fig. 5). This damper specifically resists radial motions of the gyro and its casing but does not in this instance oppose rotation. To this end the annular form has been adopted, as is clearly seen in the figures. An extension of this disk or platev 27 serves to cooperate with the damping magnets 29 to damp the pendulous action or swinging upon its Cardan mounting. The magnets are secured to a solid part, or otherwise suitably mounted and energized-the magnetic intensity being controlled and adjusted, as plainly indicated.

Fig. 5 illustrates more or less diagrammatically the wiring system by which the various parts of the apparatus are energized. 15 represents a motor generator provided with a commutator D, and also with slip-rings A. From the commutator D,-the direct current lead 60 passes to the mercury cup 24, entering the circuit re sistance box or mercury trough 26 at point V through a suitable flexible connection. Current entering at V divides and passes around through 26 in opposite directions, uniting again at X, whence it flows through lead 60' which passes downwardly as shown and is flexibly connected to a magnet 28,

from which current is led to ground by wire 61, the ground being connected with float 17. Through the float, the current within passes through the mercury to basin 18 which is the virtual point of attachment of return lead 62 which passes back to the commutator D. The current passing through magnet 28 may be shunted to a variable extent through an adjustable switch or rheostat 28'. The lead 62 is a common return wire for both alternating and direct current, being connected as shown by lead 62 to one of the slip-rings A. The other slip-ring is provided with a lead 63 having three terminals 71 which are suitably connected to the stator coils driving the gyro wheel or rotor within the wheel casing 16. In this way a single-phase current is given the effect of a 3-phase current during the starting period. It is well known that a 3-phase motor after being brought up to speed will run practically as well with a single-phase as with a 3-phase current. Consequently the switch S may be moved into the position shown in full lines after the gyro wheel has been brought up to speed, the lower switch arm then making contact with switch point 63 and being connected directly through wire 63 to one of the slip-rings A, while the upper arm of the switch is connected to terminal H of the high tension generator 43. The inductance and capacity are obviously cut out when the switch is moved into this latter position.

It may be noted that leads 60, 64 and 65 enter the compass mechanism above the mercury cup 24, while the ground and counter return wire 62 does not pass through the mercury cup at all but through the grounded float 17. The damping coil 28 and the transmitter device 26 may be energized through the same concentric mercury cup in the part 24, a series circuit arrange-- ment being shown.

To obtain the indication of the instrument atdifferent positions in the ship, the

transmitter resistance in this instance illusother, and the movable magnetic armature 33 exhibits the combined and cooperating positiveand negatlve energization of these two coils through the entire 360 degrees of are.

The method of transmitting. readings from the master compass to the repeater instruments will be clear from the foregoing especially when taken in connection with Figs. 7, 7*,8 and 8. It is to be recalledthat conductor 60, carrying the direct current of measurable volume, enters thecircuit mercury resistance trough or transmitter 26 at V, the current dividing at this point and reuniting at X whence it passes out on wire .each repeater instrument.

60. The points V-X are fixed relative to' the mercury trough and therefore move with this trough which orientates. The terminals w-b and ab of the repeater coils remain stationary however, during the orientation, with the result that the position of the points V-Xaelative to a/b and ab' alters with the orientation. This results in instituting difierent potential relations for the different relative positions noted, thus setting up currents in difi'erent conditions and amounts through the coils 32 and 32 of When only one of these coils is energized, the magnet 33 takes up a position exactly at right angles thereto; and when both coils are energized, the magnet sets itself at an angle of 45 to both coils; and as the energization fades in one coil and increases in the other, the mag net passes to intermediate positions. In Fig. 7, point V being midway between 6 and b, and the point X being midway between a and a, the coil circuits 32 and 33 are equally energized, and the magnet 33 stands in its 45 position or midway between the two coils. 'In Fig. '2' the trough 26 has turned through 45 and the terminals ab receive full difference in potential, while there is nodifierence in potential" between terminals a and 6' since they are both equidistant from V and X. Consequently a maximum current passes through coil 32, while no current passes throughcoil 32; and the magnet 33 therefore stands at right angles to coil 32.

In Fig. 8 another 45 turn has been made by the trough 26 and the coils receive the same amount of current as in Fig. 7. The

' potential relation of terminals ab' has,

however, been reversed, while that of terminals ab remains the same as before. As aresult, the armature 33 has made a 45 turn counter clockwise and stands in amidway position.

' The terminals un -b" are subjected full difference of potential andcoil 32 receives a maximum current; while between terminals wb there is no difference of potential and coil 32' has no magnetizing efl'ect. Consequently the magnet lies at right angles to coil 32 and is seen to have turned counter clockwise through another interval of 45.

A further turn of the transmitter trough 26 By tracing the course of the resistance trough 26 through the remaining 180 of arc, either continuing in the same direction from the position shown in Fig. 8 or starting from the position shown in Fig. 7 and.

In Fig. 8 the trough has. made still another turn of 45.

intense The principle of these indicating element of the master gyro compass, there is a corresponding position of the orientatin energizing terminals V and X relative to t e .fixed magnet coil terminals ab and a'b dipping into the mercury resistance trough; and that this determines a corresponding position of the magnet or armature 33. From this it is clear that the master compass indications can be reproduced in one or more repeaters with great accuracy.

A recorder is also operated on the same circuits as the indicator. This need not be gone into in detail at this time.

When a change of either heading speed or acceleration or retardation pressures are introduced in any manner a series of oscillations about the true meridian tends to. be set up in the gyrostat constitutin a hunting action, and the instrument uring thls period as to specific reading lacks an accuracy to the extent of the amplitude of the vibrations constituting the hunting action, the mean reading being, of course, accurate. These, of course, should be suppressed to make the instrument dead beat and accurate in its specific indications at all times. It is a characteristic of the gyro'scopic action, however, that each oscillation about the vertical axis is accompanied by a tendency to swing sidewise owing to the phenomenon of precession, or vica versa, the one alwaysbeing the'efiect of the other, in which ever order they occur. I have discovered if these lateral swings can be properly utilized or opposed, the hunting action can be very largely overcome, but the free rotation about the vertical axis should not in the last analysis be opposed, though when this rotation is considered as precession, it may be the element to receive direct treatment or it may be secondary as 1nd1- cated; either motion may be considered as being precession resulting from motions or impressed forces or impressed forces 1n the other plane. The annular magnet. 28 illustrates one means which allows of a very complete fulfilment of this peculiar requirement, the magnet cooperating wlth the damping plate 27; rotation not altering the number or position of the lines passing through the plate,-but even a small lateral swing alters their position and through the Foucault currents, which are thus generated in the mass of'the disk, a reaction is set up between the disk and the magnet which efiectually opposes the primary motions and and neaaoce dampens such motions directly in their inception.

The inertia weights 21 and the elastic yielding support cooperate with the float 17 and the gyroscope to prevent dancing of the floating mass, and thus permits a much closer adjustment between the magnet 28 and the disk 27. The damping magnet 29, cooperating with this same disk', damps 4 introduce quite a powerful righting moment which very greatly aids in preventing oscillations and helps to prevent hunting and also prevents inaccurate indications on the part of the instrument due to various causes, such for lnstance, as acceleration pressures.

Referring now to Fig. 12' attention should be called to the fact that the apparatus as a whole indicated at 50 at or near the axis of the ships oscillations, as stated, may be adjustably mounted as by the bell-crank lever 51 fulcrumed at 52. The horizontal dotted line 47 indicates the axis of lateral oscilla- 3 tion or roll, and the vertical dotted line may indicate the mean axis through slight angles of swing or changes in heading of the boat. The relation of the apparatus 50 to these axes is such that oscillations on the part of the ship are enabled to impart to the apparatus itself the minimum of acceleration and retardation processes due to actual motion or slinging as contradistinguished from angular motion. It will be noticed that many parts are shown herein and in certain definite relations. Some of these elements may be omitted and others operatively introduced, or the, relation of the parts may be altered, and the invention extends to such use.

Having described the invention and indicated the use and operation of the various parts in connection with such description, I claim as my invention:

1. In gyro navigation apparatus, a gyro Wheel including an electrically driven part, a float for supporting the gyro in stable equilibrium, a central guiding member independent of said float for confining the motion of the gyro and float, a mercury cup into which the guiding member dips, electric circuits for the apparatus including said guiding member and an insulating support for said guiding member.

2. In gyro navigation apparatus an electrically operated gyro wheel including an ing the gyro in sta Any ' the apparatus.

o 8. Apparatus of the character described electrically driven part, a float for supportle equilibrium, a central iding member independent of said float or confining the motion of the gyro and float, a mercury cup into which the guiding member dips, electric circuits for the apparatus including such guiding member and the float and an insulating support for such guiding member.

In gyro navigation apparatus, a gyro Wheel including an electrically driven part, a float for supporting the gyro in stable equilibrium, a central guiding member independent of said float for confining the motion of the gyro and float, a mercury' cup into which the guiding member dips, electric circuits for the apparatus including such guiding member, an insulating support for such guiding member, and an electric connection from the said mercury cup to said electrically driven part for the gyro wheel. 4. In gyro navigation apparatus, a gyro wheel, a float supporting the wheel in stable equilibrium, and a liquid supporting said float, the emerging line or perimeter of the float being materially less in diameter than the outer diameter of the main submerged portion of such float, in combination with means containing said liquid and adapted to be mounted on a ship.

5. In gyro navigation apparatus, a gyro Wheel, a Cardan support, a pendulous support for the wheel located inside and carried by the Cardan support and allowlng universal pivotal motion, a device comprising a part independent of such pendulous support for opposing motions about one axls on the part of the gyro wheel, but leaving it comparatively free .for motion about a different axis.

6. In gyro navigation apparatus, a gyro wheel, a Cardan support, a pendulous support for the wheel inside and carried by the Cardan support and allowing universal p votal motion, a. device comprising a part mdependent of such pendulous support for opposing motion about a horizontal axis on the part of the gyro wheel but leaving it comparatively free for motion about a vertical axis.

7. In gyro navigation apparatus, a gyro wheel, a float for'supporting the gyro wheel, a Cardan mounting for said float and wheel, a supporting medium for said float, a central guiding member for confining the motion of the gyro and float, the portlon of such float which emerges from the surface.

of the medium supporting the float flaring upwardly and outwardly whereby a righting moment is secured as between the gyro wheel and the Cardan supported parts of com rising the combination, with a unidirectlonal persisting device, of a Gardan supa spring-supported part provided with av a parts andthe Cardan support. 9. Apparatus of the character described comprising the combination, with a unidirectional persisting device, a ;Cardan support for the device and adjustable means arranged to damp undesirable oscillations of the supported parts without interfering with relative movements in azimuth between said parts and the Garden support. 10. Apparatus of the character described comprising the combination, with a unidirectional persisting device, a Cardan support for the device and electromagnet means arranged to damp undesirable oscillations of. the su ported parts without interfering with relative movements in azimuth between said parts and the Garden support.

11. In a gyroscopic compass, a Cardan support, a'uni-directional persisting device,-

consisting in part of a gyro wheel pendulously hung below Cardans point within such support, a suitable foundation or mounting for the apparatus and a springsu-pported part provided with a predetermined inertia relative to the weight of the compass located between the foundation and the Cardan support.

12. In a gyroscopic compass, a Cardan support, a uni-directional persisting device,

consisting in part of a gyro wheel p'endulously hung below Cardans point within such support, a suitable foundation or mounting for the apparatus, a spring-supported part provided with a predetermined inertia relative to the weight of the compass located between the foundation and the Cardan support and a pivot upon such part for carrying the said Oardan support.

' 13. In a gyroscopic compass, a Garden support, a uni-directional persisting device, consisting in part of a gyro wheel pendulously hung below Oardans point within such support,- a suitable foundation or mounting for the apparatus, and -a springsupported part provided with a predetermined inertia relative to the weight of the compass located between the foundation and the Oardan support, the gyro wheel being free and the said Cardan support being restrained as to its movements. I 14. In a gyroscopic compass, a Cardan support, auni-directional persisting device, consisting in part of a gyro wheel pendulously hung below Cardans point within tion or mounting for the apparatus-and predetermined inertia relative to the weight of the compass located between the foundation and the Gardan support, the gyro wheel being free and the said support being reforth.

and from such support, a suitable founda naiaoee strained as to movements each way from a normal central point.

15. In apparatus for performing the function of the compass, a base, a uni-direc: tional persisting device, a Cardan support for the device, and' a spring supported inertia part suitably pivoted and located between the base and the Cardan support, the connection with the spring operating with a radius adapted to be varied with changes of position of the part for the purposes set 16. In apparatus I for performing the function of the compass, a base, auni-directional persisting mechanism, a C'ardan sup- .port for the mechanism, and a spring supported inertia part suitably pivoted and located between the base and the Oardan support, the connection with the spring operating with a radius adapted to be varied withvchanges of position of the part for the purposes set forth-the point of application being adjustable with reference to the inertia part.

17. In apparatus for performing the function of the compass, a uni-directional persisting device, a Cardan support for the device, and a spring pivoted supported inertia part located between the foundation and the Cardan support, the moment of inertia of said inertia part being in effect greater than the moment of inertia of said device.

1 8. In apparatus for performing the function of the compass, an electrically operated gyrostat, a float for supporting such gyrostat in stable equilibrium, a combined 1 central guiding member and electric conductor in combination with ball-bearings surrounding the guiding member and electrical insulation between the support and the remaining portion of the apparatus.

19. In apparatus for performing the function of the compass, an electrically operated gyrostat, a float for supporting such gyrostat in stable equilibrium, a combined central guiding member and electrical conductor in combination withball-bearings surrounding the guide, and a cylindrical surface provided upon the guide .within the ball-bearings for allowing of free verti l 'movement of the float.

20. In gyro navigational apparatus, a

v gyro wheel, a Cardan support, a pendulously mounted support for the wheel carried by the Garden support and allowin universal mo tion, a device secured to said Oardan sup I port, means cooperating therewith mounted on said pendulous support for opposin radial movement of said support, and lndependently' mounted means cooperating with said device for opposing movement of the Garden support.

21, In apparatus of the character described, the combinat1on, with an electrically 1 gyrostat by flotation in the liquid, the upper or emergent portion of said buoyant member having an inverted conical form.

In a gyroscopic compass plant, a direction indicating element, a gyroscopic wheel associated therewith, rent means operatin the gyroscopic wheel, an electrical transmitting device connected with said direction indicating element, a repeater operated from said device, a source of alternatingelectric current for said gyro operating means, and also a source of direct current supply for said transmitting device and repeater, circuit connections between such supply sources, means, repeater, and device within the compass, including a flexible connection at the compass .forming-a part of such circuit connections.

23. A gyroscopic compass plant comprising a gyro wheel, alternating current means operating the gyrowheel, an electrical device other than said means connected with a direction-seeking moving element of the compass, two sources of electrical supply 01 different connections between each source and the compass and a flexible connection at the compass forming a part of such circuit connections, the device being in circuit with one of such sources through the said flexible connection. v

24. A gyroscopic compass plant comprising a gyro wheel, alternating current means operating the gyro wheel, an electrical Ilevice other than said means connected with a direction-seeking moving element of the compass, two sources of electrical supply of difi'erent electrical characteristics, circuit connections between each source and the compass, and a flexible connection at the compass forming a connection commonto each of the said sources.

25. A gyroscopic compass plant comprising a ro wheel, alternating current means operatmg the gyro wheel, an electrical device other than said means connected With a direction-seeking moving element of the compass, two sources of electrical supply of difl'erent electrical characteristics, circuit connections between each source and the compass, a flexible connection at the compass forming a connection common to each of the said sources, and a switch for dissimultaneously coupling the said sources with the flexible connection such as described.

26. A gyroscopic compass plant comprising a gyro wheel, alternating current means operating the gyro wheel, an electrical device other than said means connected with a direction-seeking moving element of the compass, a source of alternating and also of direct electric current supply consisting of I ing alternating curelectrical characteristics, circuit a single rotating element, circuit connections between such sources, means and device, and a flexible connection at the compass forming a part of such circuit connections.

27. A gyroscopic compass plant comprisa gyro wheel, alternating current means operating the gyro wheel, an electrical device other than said means connected with a direction-seeking moving element of the compass, a source of alternating and also of direct electric current supply consisting of a single rotating element impelled by a common motor, circuit connections between such sources, means and device, and a flexible connection at the compass forming a part of such circuit connections.

28. A gyroscopic compass equipment comprlsing a gyro wheel, alternating current means operating the wheel, an electric device other than said means connected with the azimuth moving element of the compass, sources of electric currents of different characteristics, one of which is alternating, circuit connections from the sources to said 'means and to said device, a flexible connecsaid means and to said device, a flexible connection at the compass forming a part of such clrcuit connections, and a conductor also formlng a portlon of sald circuit connections which is common to the a 'said diflering currents.

30. A gyroscopic compass equipment comprising a gyro wheel, alternating current means operating the wheel, an electric device other than'said means connected with the azimuth moving element of the compass, sources of electric current of difl'ering characteristics, one being of higher electrical potential than the other, circuit connections from the sources, said means and to said device, a flexibleconnection at the compass forming a part of such circuit, and a conductor also forming a portion of said circuit connections which is common to the said difl'ering currents.

31. The combination, with a ship and a master compass comprising '1 gyroscopic wheel, and electrical means for driving the wheel, the master compass being located near the axis of oscillation of'the ship, of

tom arranged to transmit indications from the master compass to the repeater compass, a unitary source of energy supply for said means and said system, and a common conductor within the compass in circuit with the said means and also the electric actuating system.

32. In gyroscopic apparatus of the character described, the combination of a gyro wheel and its journal frame mounted for limited oscillation, an element possessing inertia also mounted for movement relative to that of the wheel frame, means for damping relative movements between the frame and the element, and means for varying the j damping effect.

33. In gyroscopic apparatus of the character described, the combination of a gyro wheel and its journal frame mounted for more or less free oscillation, an element possessing inertia also mounted for movement relative to that of the wheel frame and electromagnetic means for damping relative naaacea movements between the frame and the element.

34:. In an electrically driven gyro equipment the combination, with a master compass comprising a gyro Wheel and electric driving means therefor, of a repeater compass, electric circuits connecting the master with the repeater compass, a source of electrical supply, an electric transmitter upon the master compass, and electrical con- Witnesses:

BENJAMIN W. LANcs'rRoTn, A. R. GIBBS.

ELMER A. SPERRY. 

